1. Field of the Invention
The present invention relates to complexes of the formula I, where the variables are defined as follows:    M is an element of groups 6 to 10 of the Periodic Table of the Elements,    Nu1 is selected from among O, S and Se;    Nu2, Nu3 are selected from among N and P,    A1 is N or C—R7 or Si—R7,    A2 is N or C—R8 or Si—R8,    R1 to R9 are selected from among            hydrogen,        C1-C8-alkyl, substituted or unsubstituted,        C2-C8-alkenyl, substituted or unsubstituted and having from one to 4 isolated or conjugated double bonds;        C3-C12-cycloalkyl, substituted or unsubstituted,        C7-C13-aralkyl,        C6-C14-aryl, unsubstituted or monosubstituted or polysubstituted by identical or different substituents selected from among                    C1-C8-alkyl, substituted or unsubstituted,            C3-C12-cycloalkyl,            C7-C13-aralkyl,            C6-C14-aryl,            halogen,            C1-C6-alkoxy, substituted or unsubstituted,            C6-C14-aryloxy,            SiR10R11R12 and O—SiR10R11R12;                        five- and six-membered nitrogen-containing heteroaryl radicals, unsubstituted or monosubstituted or polysubstituted by identical or different substituents selected from among                    C1-C8-alkyl, substituted or unsubstituted,            C3-C12-cycloalkyl,            C7-C13-aralkyl,            C6-C14-aryl,            halogen,            C1-C6-alkoxy,            C6-C14-aryloxy,            SiR10R11R12 and O—SiR10R11R12;where adjacent radicals R1 to R9 may be joined to one another to form a 5- to 12-membered ring;                            L1 is an uncharged organic or inorganic ligand,    L2 is an organic or inorganic anionic ligand, where L1 and L2 may be joined to one another by one or more covalent bonds,    z is an integer from 1 to 3,    R10 to R12 are identical or different and are selected from among hydrogen, C1-C8-alkyl, C3-C12-cycloalkyl, C7-C13-aralkyl and C6-C14-aryl.
The present invention also relates to a process for preparing the complexes of the present invention from ligands of the formula II, and to a process for preparing ligands of the formula II.
The present invention additionally relates to a process for preparing supported polymerization catalysts using a complex of the formula I and to a process for the polymerization or copolymerization of olefins using the supported catalysts of the present invention.
Finally, the present invention relates to a process for the emulsion polymerization and emulsion copolymerization of olefins using a complex of the formula IV.
2. Description of the Background
Polymers and copolymers of olefins are of great economic importance because the monomers are readily available in large quantities and because the polymers can be varied within a wide range by variation of the production process or the processing parameters. The catalyst used is of particular importance in the production process. Apart from Ziegler-Natta catalysts, there is increasing interest in single-site catalysts in which central atoms which have been examined in detail include not only Zr as, for example, in metallocene catalysts (H.-H. Brintzinger et al., Angew. Chem. 1995, 107, 1255) but also Ni or Pd (WO 96/23010) or Fe and Co (e.g. WO 98/27124). The complexes of Ni, Pd, Fe and Co are also referred to as complexes of late transition metals.
Metallocene catalysts have disadvantages for industrial use. The most frequently used metallocenes, i.e. zirconocenes and hafnocenes, are sensitive to hydrolysis. In addition, most metallocenes are sensitive to many catalyst poisons such as alcohols, ethers or CO, which makes careful purification of the monomers necessary.
While Ni or Pd complexes (WO 96/23010) catalyze the formation of highly branched polymers which are of little commercial interest, the use of Fe or Co complexes leads to the formation of highly linear polyethylene having very low proportions of comonomer.
Furthermore, complexes by means of which ethylene can be polymerized or copolymerized in the presence of water have been examined.
WO 98/42664 describes complexes of the formula A and closely related derivatives containing salicylaldimine ligands and their use for the polymerization of olefins.
WO 98/42665 describes complexes of the formula B and closely related derivatives and their use for the polymerization of olefins.
In the complexes of both the formulae A and B, the radical R on the imine nitrogen is a C1-C11-alkyl group or an ortho-substituted phenyl group. However, their activity is still in need of improvement.
It is also known that the complexes of the formulae A and B remain polymerization-active in the presence of small amounts of water, without the catalytic activity being adversely affected (WO 98/42664, in particular page 17, line 14 ff; WO 98/42665, p. 16, line 13). However, these amounts of water must not exceed 100 equivalents, based on the complex (WO 98/42664, page 17, lines 33-35; WO 98/42665, page 16, lines 30-31). Under these conditions, however, it is not possible to carry out an emulsion polymerization.
WO 98/30609 discloses derivatives of A which are suitable for the polymerization of ethylene and propylene. Their activity in this respect is not always satisfactory.
EP-A 0 874 005 discloses further polymerization-active complexes. These complexes are preferably titanium complexes containing salicylaldimine ligands. These too bear phenyl substituents or substituted phenyl substituents on the aldimine nitrogen (pages 18-23) or else the aldimine nitrogen is built into a 6-membered ring (pages 31-32). However, they have a high sensitivity to polar compounds such as water, alcohols or ethers.
In DE-A 199 61 340, published on . . . , it is shown that complexes of late transition metals of the formulae C and D where R to R″″′ are each hydrogen, alkyl, C7-C13-aralkyl or C6-C14-aryl, and mixtures thereof are suitable for polymerizing ethylene by emulsion polymerization. However, the activities are still in need of improvement. In A. Held et al., J. Chem. Soc., Chem. Commun. 2000, 301, it is shown that complexes of the formula C in which R is phenyl and R″ is an SO3— group are suitable for polymerizing ethylene in an aqueous medium. The activity of C is still not optimal.
Owing to the great commercial importance of polyolefins, the search for very versatile polymerization-active complexes having the highest possible activity continues to be of great importance.